This invention relates to a process for the manufacture of polycarbonate powder.
The use of plastics in powder form is gaining increasing industrial importance. There is therefore a requirement for also isolating polycarbonates in the form of a uniform powder from their solutions in organic solvents in an industrially feasible process. Such powders should have as high a bulk density as possible and should be as free of impurities as possible.
Polycarbonates are in most cases manufactured from aromatic dihydroxy compounds and phosgene or bis-chlorocarbonic acid esters by thoroughly mixing an aqueous-alkaline solution of the bisphenol with a solution of the phosgene or bis-chlorocarbonic acid ester in a water-immiscible organic solvent, whereupon the polycarbonate formed dissolves in the organic solvent. Usually, methylene chloride is used as the solvent. After separating off the aqueous phase, a solution of the polycarbonate in the organic solvent is left.
It is thus an object of the present invention to provide a process to isolate the polycarbonate from a solution in an organic solvent, such as for example from the solution obtained during its manufacture, in the form of a homogeneous powder of high bulk density.